1. Field of the Invention
The present invention relates to a vacuum apparatus and, more particularly, to a vacuum cleaner used for cleaning up, for example, fallen leaves, wooden chips, and waste, and to a fan casing for the same.
2. Description of the Related Art
In a vacuum cleaner used for cleaning up fallen leaves, wooden chips, waste, and other items (U.S. Pat. No. 5,245,726 is an example of such a device), incoming materials are passed through a fan casing while sliding against an inner surface of the fan casing; hence, the inner surface of the fan casing is apt to wear due to the contact with the incoming materials. If the fan casing is subjected to continued use for an extended period of time without being replaced at appropriate intervals, then the fan casing may incur serious damage or incoming materials may leak out, or other problems may arise during operation of the device.
Accordingly, the present invention has been made with a view toward solving the problems associated with the related art, and it is an object thereof to provide a vacuum apparatus that enables a user to easily check from outside a degree of wear on an inner surface of a fan casing that is caused by frictional contact with incoming materials so as to allow the user to easily know the appropriate time to replace the fan casing.
To this end, the present invention provides a vacuum apparatus equipped with a fan casing through which an incoming material passes, wherein an outer surface of the fan casing is provided with a recessed portion that extends toward the inner surface of the fan casing. The recessed portion has the appearance of a protrusion when viewed from inside the fan casing.
According to the present invention, if incoming materials frequently pass through the fan casing, then the recessed portion wears more quickly than the rest of the inner surface of the fan casing. Therefore, the user will be able to easily know when to replace the fan casing by visually checking the recessed portion from outside the fan casing. If the wear on the recessed portion advances until a hole finally opens in the recessed portion, then a noise (e.g. a whistle-like noise) that is different from normal operating noises will be produced, so that the time to replace the fan casing can be known audibly as well as visually.
In a preferred embodiment of the present invention, the depth of the recessed portion can be set so that an outer surface of the recessed portion reaches the inner surface of the fan casing, or the outer surface of the recessed portion is positioned farther inward than the inner surface of the fan casing.
Furthermore, the number of the protrusions is not limited to one; any appropriate number of recessed portions may be provided along the outer periphery of the fan casing.